In the dry pressing of parts from powdered materials, in particular cylindrical parts with large length to wall thickness ratios, the practical net shape limit under the present technology is approximately 4 to 1. For example, a cylindrical shape with a wall thickness of about 0.100 inches has a practical maximum length of about 0.400 inches. Once this ratio is exceeded, a variation of green density along the length of the cylinder results in distortion and porosity at the center along the length of the cylinder during the sintering process.
Since parts with higher length to wall thickness ratios higher than 4:1 are required in a variety of applications, a process by which such cylindrical ceramic parts can be produced without distortion and porosity would be an advancement in the art.